1. Field of the Invention
The present invention relates generally to distributing media channels, and more particularly, to switching between media channels.
2. Related Art
Users of analog televisions are accustomed to rapidly switching between channels to choose different television programs. Traditionally, analog televisions are equipped with an internal tuner for switching channels that are received via over-the-air broadcast signals or cable television (CATV) signals. To switch channels, the internal tuner tunes to a different channel frequency and locks onto the signal. The television then processes the signal and displays the channel on a cathode ray tube (CRT) device, liquid crystal display (LCD), plasma screen, etc.
Sometimes a set-top box (STB) is used in conjunction with a television. In such systems, the STB includes an internal tuner that operates in a manner similar to that of a traditional internal tuner; that is, the STB tuner switches between channels by tuning to a new channel frequency and locking onto the signal. The STB then provides the desired channel to the television for display. STBs often employ additional hardware and/or software beyond that found in a traditional television such as, for example, a processor to decode scrambled premium channels.
More recently, television channels are also distributed over a packet switching network such as the Internet. This television distribution technology, referred to as Internet Protocol Television (IPTV) or video-over-IP, does not use different frequencies for each television channel. Rather, a different data stream is transmitted over the network for each television channel. The H.264 standard, also referred to as MPEG-4 AVC (Advance Video Control), is often used for transmitting data streams in IPTV. In the H.264 standard, a data stream comprises multiple groups of pictures (“GOP”) each having an initial frame or intraframe (“I-Frame”) followed by a series of associated consecutive delta or image frames (“Δ-Frame”).
To begin viewing the data stream, an I-Frame must first be processed. Unfortunately, in typical systems when switching channels, before a user can begin viewing a channel, a user must wait until the broadcast source finishes transmitting the current GOP and transmits the I-frame of a new GOP. Such a delay is commonly several seconds, which is significantly longer than the delay associated with the switching of television channels in over-the-air or CATV systems. Such relatively greater delays to switch between channels may negatively impact adoption of IPTV.